Device for reducing the thrust of steerable propellers

ABSTRACT

A device for reducing the thrust of steerable propellers. The device is composed of a conduit which extends from above the watercraft to a position in juxtaposition the propeller and is adapted to convey a gas to the negative pressure zone around the propeller to control the thrust generated by the propeller movements in the water.

I United States Patent [1 1 [111 3, 6

Wacker Dec. 9, 1975 DEVICE FOR REDUCING THE THRUST 0F [56] References Cited STEERABLE PROPELLERS UNITED STATES PATENTS [75] Inventor: Gerd Wacker, Winnigen, Mosel, 3,434,447 3/1969 Christensen et al. 115/.5 R

Germany Primary ExaminerTrygve M. Blix 73 A Sch tt 1- sslgnee 1x5? g fiigg KG Assistant Examiner-Gregory W. OConnor Attorney, Agent, or FirmWoodhams, Blanchard and [22] Filed: Mar. 22, 1974 Flynn [21] Appl. No.: 453,690 [57] ABSTRACT i A device for reducing the thrust of steerable propel- F 1 [30] orelgn Apphcamn Pnonty Data lers. The device is composed of a conduit which ex- Apr. 9, 1973 Germany 2317731 tends from above the Watercraft to a position in juxta position the propeller and is adapted to convey a gas g 115/35 115/18 $2; to the negative pressure zone around the propeller to 58 Field of Search 115/35, 34 R, 17, .5 R, generated b the propeller move' 3 Claims, 2 Drawing' Figures US. Patent Dec. 9 1975 Sheet 1 of2 3,924,556

wax/11??! 1 W an an DEVICE FOR REDUCING THE THRUST STEERABLE PROPELLERS FIELD OF THE INVENTION The invention relates to a device for reducing the thrust of steerable propellers which are pivotable about a vertical axis or the like for the purpose of steering of watercrafts.

BACKGROUND OF THE INVENTION The basic purpose of the invention is to regulate the thrust of steerable propellers or the like which are driven by a nonregulatable propelling plant. Such nonregulatable propelling device may, for example, exist if a propeller is driven by an electric motor which must run at a constant rotational speed because it must for example also drive a generator. A change-speed gear or a device for a blade adjustment on the propeller is expensive and is to to be avoided in this instance. Of course, the invention is not to be limited to the above exemplarily described embodiment but is intended for use with all drive mechanisms, the rotational speed of which cannot be regulated.

The term regulatable means in the sense of the invention a controllable feeding of air or the like. As a regulating member one can use, according to the invention, a pipe or the like which can be lowered into the underpressure field of the propeller. It is also possible to use a stationary pipe or a corresponding line which extends into the underpressure field, which pipe or line is more or less opened by a closure member, for example a valve. It is also possible to use a regulatable air pump. Air will usually be the regulating medium, however, the invention is not to be limited to this.

A more advantageous embodiment is a device wherein the pipe is fixed to the pivotal propeller housing and movable therewith.

The invention can also be used for regulatable propellers so to speak as an emergency brake.

BRIEF DESCRIPTION OF THE DRAWINGS The invention is described in connection with exemplary embodiments illustrated in the drawings, in which:

FIG. 1 illustrates as an example a watercraft drive mechanism having a steerable propeller in which the device of the invention does not swing with the propeller; and

FIG. 2 illustrates a steerable propeller in which the device of the invention swings with the steerable propeller.

DETAILED DESCRIPTION For example, at the stern of a watercraft 1 in a chamher 2 there is arranged a steerable propeller 3 of the conventional type pivotably about a vertical axis. The steerable propeller is driven by a polyphase induction motor or altemating-current motor 4 the speed of which is not regulatable through known and, therefore, not illustrated transmission elements. For regulating or for reducing the thrust of the propeller 7, a pipe 5 is provided through which air can be fed from the atmosphere into the underpressure or negative pressure field of the propeller. To regulate the supplied amount of air, a valve 6 or other like adjustable closing element is provided on the pipe 5. Instead of sucking the air in from the atmosphere, the pipe 5 can also be connected to a regulatable air pump. Due to the fact that more or less air is sucked in by the propeller, its thrust is reduced more or less, and is, therefore, regulated. In the present example of FIG. 1, a stationary or fixed pipe is provided so that the greatest thrust reduction is provided only in the normal position of the steerable propeller, while the thrust reduction effect is lowered depending on the angle of traverse of the steerable propeller.

FIG. 2 illustrates a steerable propeller-10, the underwater part 11 of which is supported swingably in a conventional manner in the above-water housing 12 for controlling the watercraft. The propeller 13 is driven through a hollow-verticaldrive-shaft 14 which transmits the torque from the above-water housing into the underwater part. At the lower end of the drive shaft there is provided in a.conventional manner a bevel gearing 15 for transmitting the torque from the drive shaft onto the horizontally supported propeller shaft 16. The drive mechanism for the drive shaft and for the control movement of the underwater part is known and, therefore, does not need to be described in detail. The steerable propeller is driven like in the above-described example by a nonregulatable motor, for example an electric motor such as is illustrated in FIG. 1. To regulate the propeller thrust, a feed pipe 17 is provided which is arranged in a central bore of the drive shaft 14 and which leads into the underwater housing of the steerable propeller. The feed pipe is connected to an outlet in the underwater part at the front end 18 thereof, the outlet being defined by a short feed pipe 19. The outlet opening is protected by a caplike cover 20 at the forward end of the pipe so that no water can penetrate into the short feed pipe 19 due to the thrust and the air from the outlet pipe is fed to the underpressure field behind the caplike cover 20 (arrow 21). Through this arrangement, the suction side of the propeller can recieve air in any position, as is schematically illustrated by the arrows 21. The volume of feeding and thrustreducing air can be controlled by a valve 22 which is provided in the feed pipe at a location which is advantageous for the operator.

Although particular preferred embodiments of the invention have been disclosed in detail for illustrative purposes, it will be recognized that variations or modifications of the disclosed apparatus, including the rearrangement of parts, lie within the scope of the present invention.

The embodiment of the invention in which an exclusive property or privilege is claimed are defined as follows:

1. A device for controlling the thrust of a steerable propeller pivotal about a vertical axis for the purpose of steering a watercraft, comprising:

a rotatably driven electric motor having a substantially constant output speed; and

means defining a gas guide which extends into a suction zone of said propeller, at least when said propeller is swung into a certain position, valve means for providing a gas flow to said suction zone which is variable independent of the speed of said rotatably driven motor, said gas guide means being adapted to convey a gas therethrough from said valve means to thereby control the thrust of said propeller driven by said rotatably driven motor.

2. A device for controlling the thrust of a steerable propeller pivotal about a vertical axis for the purpose of steering a watercraft, comprising:

a rotatably driven motor having a substantially constant output speed; and

means defining a gas guide which extends into a suction zone of said propeller, at least when said propeller is swung into a certain position, valve means for providing a gas flow to said suction zone which is variable independent of the speed of said rotatably driven motor, said gas guide means being adapted to convey a gas therethrough from said valve means to thereby control the thrust of said propeller driven by said rotatably driven motor, said gas guide means tenninating in the suction zone at a location coaxial with the axis of rotation of said propeller.

3. A device for controlling the thrust of a steerable propeller pivotal about a vertical axis for the purpose of steering a watercraft, comprising:

a rotatably driven motor having a substantially constant output speed; and

means defining a gas guide which extends into a suction zone of said propeller, at least when said propeller is swung into a certain position, valve means for providing a gas flow to said suction zone which is variable independent of the speed of said rotatably driven motor, said gas guide means being adapted to convey a gas therethough from said valve means to thereby control the thrust of said propeller driven by said rotatably driven motor, said gas guide means consisting of a feed pipe mounted internally of said steerable propeller and which extends into an underwater part of the interior of said steerable propeller, said gas guide means further including a short feed pipe extending from said interior of said steerable propeller into said suction zone of said propeller at a location 00- axial with said axis of rotation of said propeller. 

1. A device for controlling the thrust of a steerable propeller pivotal about a vertical axis for the purpose of steering a watercraft, comprising: a rotatably driven electric motor having a substantially constant output speed; and means defining a gas guide which extends into a suction zone of said propeller, at least when said propeller is swung into a certain position, valve means for providing a gas flow to said suction zone which is variable independent of the speed of said rotatably driven motor, said gas guide means being adapted to convey a gas therethrough from said valve means to thereby control the thrust of said propeller driven by said rotatably driven motor.
 2. A device for controlling the thrust of a steerable propeller pivotal about a vertical axis for the purpose of steering a watercraft, comprising: a rotatably driven motor having a substantially constant output speed; and means defining a gas guide which extends into a suction zone of said propeller, at least when said propeller is swung into a certain position, valve means for providing a gas flow to said suction zone which is variable independent of the speed of said rotatably driven motor, said gas guide means being adapted to convey a gas therethrough from said valve means to thereby control the thrust of said propeller driven by said rotatably driven motor, said gas guide means terminating in the suction zone at a location coaxial with the axis of rotation of said propeller.
 3. A device for controlling the thrust of a steerable propeller pIvotal about a vertical axis for the purpose of steering a watercraft, comprising: a rotatably driven motor having a substantially constant output speed; and means defining a gas guide which extends into a suction zone of said propeller, at least when said propeller is swung into a certain position, valve means for providing a gas flow to said suction zone which is variable independent of the speed of said rotatably driven motor, said gas guide means being adapted to convey a gas therethough from said valve means to thereby control the thrust of said propeller driven by said rotatably driven motor, said gas guide means consisting of a feed pipe mounted internally of said steerable propeller and which extends into an underwater part of the interior of said steerable propeller, said gas guide means further including a short feed pipe extending from said interior of said steerable propeller into said suction zone of said propeller at a location coaxial with said axis of rotation of said propeller. 